linux-kernel - Re: [PATCH] selftests: livepatch: Fix it to do root uid check and skip

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Message-ID: <20191216083754.hsmdd6jt2zzjmksz@pathway.suse.cz>
Date:   Mon, 16 Dec 2019 09:37:54 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     jpoimboe@...hat.com, jikos@...nel.org, mbenes@...e.cz,
        joe.lawrence@...hat.com, shuah@...nel.org,
        live-patching@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests: livepatch: Fix it to do root uid check and
 skip

On Fri 2019-12-13 10:52:32, Shuah Khan wrote:
> On 12/13/19 1:34 AM, Petr Mladek wrote:
> > On Thu 2019-12-12 18:56:17, Shuah Khan wrote:
> > > livepatch test configures the system and debug environment to run
> > > tests. Some of these actions fail without root access and test
> > > dumps several permission denied messages before it exits.
> > > 
> > > Fix it to check root uid and exit with skip code instead.
> > 
> > It works when I run the tests directly, e.g.
> > 
> > $> cd tools/testing/selftests/livepatch
> > $> ./test-livepatch.sh
> > 
> > But I still get an error from the selftest framework when running
> > make run_tests:
> > 
> > $> make run_tests
> > TAP version 13
> > 1..5
> > # selftests: livepatch: test-livepatch.sh
> > /mnt/kernel/linux/tools/testing/selftests/kselftest/runner.sh: line 43: /dev/stdout: Permission denied
> > not ok 1 selftests: livepatch: test-livepatch.sh # exit=1
> > # selftests: livepatch: test-callbacks.sh
> > /mnt/kernel/linux/tools/testing/selftests/kselftest/runner.sh: line 43: /dev/stdout: Permission denied
> > not ok 2 selftests: livepatch: test-callbacks.sh # exit=1
> > # selftests: livepatch: test-shadow-vars.sh
> > /mnt/kernel/linux/tools/testing/selftests/kselftest/runner.sh: line 43: /dev/stdout: Permission denied
> > not ok 3 selftests: livepatch: test-shadow-vars.sh # exit=1
> > # selftests: livepatch: test-state.sh
> > /mnt/kernel/linux/tools/testing/selftests/kselftest/runner.sh: line 43: /dev/stdout: Permission denied
> > not ok 4 selftests: livepatch: test-state.sh # exit=1
> > # selftests: livepatch: test-ftrace.sh
> > /mnt/kernel/linux/tools/testing/selftests/kselftest/runner.sh: line 43: /dev/stdout: Permission denied
> > not ok 5 selftests: livepatch: test-ftrace.sh # exit=1
> > 
> > The same problem is also in linux-next. Is this a know problem, please?
> > 
> > 
> 
> This isn't a known issue.
> 
> I am not seeing this problem on 5.5-rc1 and on linux-next with top
> commit 32b8acf85223448973ca0bf0ee8149a01410f3a0 (HEAD -> master, tag:
> next-20191213
> 
> I am curious what could be diffent in your env. that is causing it.

I did the test in kvm. I was connected there via ssh as "root".
I tested the normal user with "su - user".

It seems that in this case /dev/stdout still points to a
pseudo-terminal that is accessible only by root:

#> su - user
$> echo hello >/dev/stdout
-bash: /dev/stdout: Permission denied
$> ls -l /dev/stdout
lrwxrwxrwx 1 root root 15 Dec 13 16:08 /dev/stdout -> /proc/self/fd/1
$> ls -l /proc/self/fd/1
lrwx------. 1 user users 64 Dec 16 09:27 /proc/self/fd/1 -> /dev/pts/1
$> ls -l /dev/pts/1
crw--w---- 1 root tty 136, 1 Dec 16 09:27 /dev/pts/1

I do not see this problem when I ssh to the machine as
the normal "user".


Best Regards,
Petr